Method of processing silicone wastes

ABSTRACT

A method of processing polymer materials, highly filled or otherwise to recover cyclic structures or monomers. The method involves providing a vessel having a heated side wall, an agitator, and at least one of an additional heated structure, other than the heated side wall, within the vessel and means for forming a thin coat of material processed in the vessel on said heated side wall. A polymer material is fed into the vessel and heated to a sufficient temperature to cause depolymerization of the polymer material into cyclic structures or monomers. The cyclic structures or monomers are removed from the vessel and collected. The method does not require the use of a solvent.

RELATED APPLICATION

The present application is based upon U.S. Provisional PatentApplication Ser. No. 60/042,143, filed Apr. 3, 2008 to which priority isclaimed under 35 U.S.C. §120 and of which the entire specification ishereby expressly incorporated by reference.

TECHNICAL FIELD

The present invention relates to silicone wastes and more particularlyto methods for processing silicone wastes.

BACKGROUND ART

Silicone products such as silicone fluids, emulsions, sealants, rubber,tubing, etc. are currently being recycled by a catalyticdepolymerization process that involves heating the silicone material toconvert it into cyclic compounds which are recovered for reuse. Thiscurrent process employs a batch vessel or batch reactor with heatedsidewalls that transfers heat to the mixture therein and elutes, undervacuum, the desired oligomer—a cyclic siloxane.

These current batch operations are limited due to the minimal exposedarea from which the oligomer may distill. Utilizing any heated surfaceabove the liquid line requires sufficient agitation to propel materialonto this surface. This becomes increasingly less effective as theoligomer elutes and product viscosity increases. Traditionally, this isovercome with the addition of a solvent into which the polymer isdissolved or suspended. Further, the heated surface below the liquidline initiates foaming and carry-over as the oligomer elutes through theincreasingly viscous material. Again, the use of a solvent can preventsome carry-over by reducing the viscosity of the material to berecycled. However, the solvent, itself, can distill or carry-over withthe desired oligomer requiring subsequent separation. Once theconversion to oligomer is complete, the fill material that remains mustbe separated from the often expensive solvent.

These current processes are therefore further hindered in that theycannot take the material to dryness in a single distillation step.

The present invention provides improved methods for processing siliconewastes which employ unique agitation to effectively utilize and/orincrease the surface area within the reactor. This not only increasesefficiency in depolymerization and oligomer recovery but also acts toprevent foaming without the need for solvent, allowing increaseddistillation rates and improved product put-through as the entirereactor volume is utilized for product alone not product plus solvent.

The present invention also provides a single-pass operation, taking thereactor contents from siloxane material to dry filler and/or catalystregardless of the viscosity, fill content, or molecular cross-linking ofthe initial material

DISCLOSURE OF THE INVENTION

According to various features, characteristics and embodiments of thepresent invention which will become apparent as the description thereofproceeds, the present invention provides a method of recycling siliconepolymers which involves:

providing a vessel having a heated side wall, an agitator, and at leastone of:

-   -   i) an additional heated structure, other than the heated side        wall, within the vessel; and    -   ii) a means for forming a thin coat of material processed in the        vessel on said heated side wall;    -   feeding a polymer material into the vessel;    -   heating the polymer material in the vessel to a sufficient        temperature to cause depolymerization of the polymer material        into cyclic structures or oligomers; and collecting the        oligomers.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be described with reference to the attacheddrawings which are given as non-limiting examples only, in which:

FIG. 1 is a perspective view of a commercially available thermal augeror thermal screw that can be used in accordance with the presentinvention.

FIG. 2 is a diagram of a laboratory reactor that can be used inaccordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is directed to methods of recycling siliconepolymer materials, highly filled or otherwise, in the absence ofsolvent, which methods have improved processing rates and percentrecovery as compared to prior art methods. The recycling of siliconematerials according to the present invention can be conducted in batchesas well as in a continuous addition process.

The method comprises the catalytic depolymerization of a material withina heated vessel or reactor. The vessel or reactor can include a heatedor non-heated agitator and/or a structure that forms, on a heatedsurface, a thin coat of the material being processed. The polymer andcatalyst are fed into the vessel or reactor and heated to a sufficienttemperature to undergo depolymerization into oligomers. The oligomersare collected in the vapor phase and condensed.

As the oligomer is collected and the reactor contents deplete,additional polymer may be supplied to the reactor, further utilizing theinitial catalyst. The unique reactor design affords the ability to takethe reactor contents to dryness resulting in a free-flowing powder. Inone embodiment of the invention, the polymer undergoes acidic catalysisprior to neutralization and alkaline depolymerization in the reactor. Inanother embodiment of the invention the catalyst is prepared through aring-opening reaction of the cyclic oligomer and the addition of analkali metal to both ends of the opened ring. In another embodiment ofthe invention an alkali hydroxide is introduced into the reactor forin-situ formation of the catalyst from the polymeric material, itself.

One embodiment of the present invention provides continuous addition toa “wet” reactor bed. Alternatively, the present invention allows for theaddition of polymer to a dried reactor bed for “re-wetting” of driedfill material and catalyst, from a previous batch, as well as allowingfor traditional batch processing whereby the contents are taken todryness and discharged prior to introducing a fresh batch with freshcatalyst. The method can be used to process silicone materials such asfluids, emulsions, tubing, gloves, bands, sealants, rubber, or otherhighly viscous materials with improved yield and efficiency overtraditional batch operations

The methods of the present invention involve the use of mixing methodsand apparatus in the depolymerization process that promote the formationof a thin film of the silicone material on heated surfaces of theprocessing equipment such that heat transfer surfaces are optimized andconversion and recovery is enhanced. The catalyst employed is created bya ring-opening reaction of the cyclic oligomer and the addition of analkali metal to both ends of the resulting open ring. Thus a quantity ofthe cyclics can serve as a vehicle for delivery of an alkalidisilanolate catalyst. In addition, the present invention allows foracid catalysis of materials, to effectively pre-digest the polymer,followed by a neutralizing step and then depolymerization in the reactorusing the above stated alkali disilanolate catalyst.

The present invention also allows for the introduction of an alkalihydroxide, either dissolved in a suitable solvent or directly added tothe reactor, for in-situ formation of the alkali silanolate catalyst.This in-situ formation of catalyst may follow acid pre-digestion andneutralization. Although corrosion studies conducted during the courseof the present invention suggest that acid-catalyzed depolymerizationresults in excessive wear on the traditional materials of constructionfor heat transfer surfaces like stainless or carbon steel, one skilledin the art can envision a reactor made of or partially made of glass ornon-reactive metals would permit the use of acid catalysis.

These features of the present invention are applicable to batch typesystems, such as mixed vessels or tanks, and/or continuous processapparatus such as a thermal auger or thermal screw (or similarequipment) as discussed below.

According to the present invention the processing equipment is selectedand/or configured to: 1) mix and/or spread the material being processedto create a thin film against a heated surface that improves thetransfer of the heat into the material; and 2) improve eluting of theoligomer. These features are applicable to both batch and continuousprocesses according to the present invention. These processes includeeither the use of a suitable agitator that spreads the silicone materialonto a heated surface and/or an agitator as the heated surface itself.In the former, the agitator acts to spread the vessel contents into athin film upon a heated surface from which the formed oligomers may theneasily distill. In the latter description, a thermal auger or thermalscrew type device (or similar equipment) provides the mixing andspreading by employing breaker bars that assist in distributing materialalong the surface of the auger or screw type device while incorporatingincreased surface area for the heat transfer, film formation, anddistillation of oligomer.

FIG. 1 is a perspective view of a commercially available thermal augeror thermal screw that can be used in accordance with the presentinvention. The thermal auger or thermal screw shown in FIG. 1 iscommercially available from Bethlehem Corporation, Easton, Pa. Thethermal auger (or thermal screw) used in the present invention includesa jacketed vessel 1 which houses an agitator 2 that is provided withradially extending paddles 3. The jacketed vessel 1 of the thermal auger(or thermal screw) can be configured with an inlet and an outlet (notshown) that are used to pass a heat-transfer medium through the jacketin a conventional manner. The inlet and outlet can be provided at anydesired location in the jacket. The paddles 3 of the agitator 2 arelikewise provided with hollow chambers with fluid channels thatcommunicate with the drive or rotary shaft 4 and allow for a heatedheat-transfer medium to pass and circulate through the paddles 3. Theheated heat-transfer medium can be circulated through the rotary shaft 4and paddles 3 through an inlet 5 and outlet 6 that are coupled to therotary shaft 4 as depicted in FIG. 1.

The thermal auger (or thermal screw) includes a material inlet 7,through which silicone wastes can be fed into the thermal auger (orthermal screw). Breaker bars 8 can be provided which extend between thepaddles 3 and break up material that gets caught between adjacentrotating paddles 3.

In operation, silicone materials are continuously fed into the thermalauger (or thermal screw) through the material inlet 7. The siliconematerials become mixed by the paddles 3 of the agitator 2 and contactthe heated inner surface of the jacketed vessel 1 and the heatedsurfaces of the paddles 3. As the polymer is heated it becomes convertedunder catalytic action into cyclic oligomers that are distilled off. Thedistilled oligomers move through a vapor outlet 9 and are then condensedand collected outside of the jacketed vessel 1. Additional siliconematerial may be fed continuously into the jacketed vessel 1 as theoligomers elute. Upon completion of the conversion, filler content fromthe silicone material and the catalyst charge remains in the jacketedvessel 1 and can be propelled by action of the auger flights towardoutlet 10.

The use of a thermal auger (or thermal screw) system provides a largesurface area from which the formed oligomers may distill. Such systemsare much more energy efficient than current batch operations throughincreased distillation rates, enhanced recovery, and single-passoperation. The overall capital cost for an auger system is believed tobe much lower than the number of batch systems that would be requiredfor a processing system with the same capacity. Reductions in operatingcosts are also realized through improved yields and by effectively usinga single catalyst charge for multiple batches in the continual additionprocess.

During the course of the present invention it was determined that inaddition to providing a large collective surface area for heat transferinto the silicone wastes, a thermal auger (or thermal screw) could beconfigured to, in addition to mixing the silicone wastes, spread thesilicone wastes to form a thin coat on the heated surfaces of thereactor. In the case of a thermal auger (or thermal screw), the jacketvessel 1 could have a cylindrical shape or at least an internal circularcross-sectional shape that provides a clearance between the innersurface of the vessel jacket 1 and the outer edges of the paddles 3 sothat rotation of the paddles 3 can assist in spreading the siliconewastes and forming a thin film on the inner surface of the vessel jacket1. Likewise, the paddles 3 could be configured, e.g., to have an axialdimension at their outer edges, which assist in spreading the siliconewastes and forming a thin film on the inner surface of the vessel jacket1. It is also within the scope of the present invention to configure thebreaker bars 8 and/or paddles 3 so that the clearance between thebreaker bars 8 and paddles 3 assists in spreading the silicone wastesand forming a thin film on at least part of the surfaces of the paddles3 as the paddles rotate past the breaker bars 8.

As in the case of thermal augers (or thermal screws) discussed above,for batch processing of silicone wastes, a vessel with a heating meanssuch as a jacket through which a heated heat-transfer medium cancirculate, electrical heated bands, or other suitable heating means canbe used in conjunction with an agitator that has blades or paddles orother structure that is configured to assist in spreading the siliconewastes and forming a thin film on the inner surface of the vessel.Alternatively, or in addition, the agitator can be configured to beheated in order to provide additional heated surfaces for the siliconewastes to contact. For example, the agitator can be provided withpaddles or blades that have cavities through which a heatedheat-transfer medium can flow.

In addition to providing means to increase the heated surface area ofthe processing equipment which is contacted by the silicone materialduring processing and providing for means to spread and form a thin filmof the silicone wastes on the heated surfaces, according to the presentinvention the silicone wastes materials can be subject to size reductionbefore or after being fed into the processing equipment. For example,the silicone wastes materials can be ground, milled, shredded, etc.prior to being fed into the processing equipment. Alternatively, or inaddition, the processing equipment could be provided with internalmechanisms such as auxiliary grinders, choppers, shredders, or cuttingblades or structure such as cutting blades of fins on the agitatorblades or paddles that are designed and configured to assist in breakingdown large pieces, masses or volumes of the silicone waste materialsduring processing.

It is noted that a thermal auger or thermal screw has been used as anexample of processing equipment that can be used for continuousprocessing; the invention is not limited to the use of a thermal augeror thermal screw. Other continuous and stage-wise equipment can be usedwhich can be heated and provided with heated agitators and/or devicesthat spread thin films of material being processed on heated surfaces ofthe equipment.

It is further noted that while the present invention is primarilydirected to processing silicone waste materials, the equipment andtechniques described herein can be used to process and depolymerizeother types of polymers.

The silicone cyclics that are obtained by the process of the presentinvention can be offered as commercial products or otherwise upgraded toa polymer.

FIG. 2 is a diagram of a laboratory reactor that can be used inaccordance with the present invention. This laboratory reactor, whichwas used and is referred to in the working example below, includes areactor 12 that was constructed using a 12 L glass round-bottom vesselfitted with a stainless steel reactor head 13. The reactor 12 was tiltedin a heating mantle 14 such that the agitator is approximately 30degrees from horizontal. The portion of the reactor 12 above the heatingmantle was fitted with a heated jacket (not shown). The reactor 12 wasalso fitted with a prototype expandable agitator 15 to conform to theshape of the reactor 12 and allow distribution of material into a thinfilm against the inner walls of the reactor 12. The agitator 15 wasrotated by an air drive motor 16. A spiral glass condenser 17,temperature regulated by an external chiller (not shown), was used forcapture of the oligomer and delivery through a vacuum manifolddistillation receiver 18.

The following non-limiting examples will more fully illustrate theembodiments of this invention. All parts, percentages and proportionsreferred to herein and in the appended claims are by weight unlessotherwise indicated.

Example 1 Continuous Addition

A 1000 g sample of siloxane sealant was added to a reactor 12 fittedwith an apparatus to allow continual addition of two, separate, 1000 gsamples of additional siloxane sealant from a small external storagevessel (See FIG. 2). Also added to the reactor 12 were 291 g of apreviously prepared potassium silanolate catalyst equivalent to 7% KOHby mass of the siloxane content in the initial 1000 g charge. Thereactor 12 was sealed and heating and agitation applied. After heatingfor 15 minutes, vacuum was applied. Distillation and recovery ofsiloxane cyclics began at a temperature of 140° C. and an absolutevacuum of 15 mm Hg. The distillation rate increased as the reactortemperature approached 200° C. Reactor temperature and vacuum weresubsequently maintained at these conditions.

Upon recovery of approximately 300 g of cyclics, equivalent to 50% ofthe total siloxane component of the initial charge, the contents of theattached storage vessel were slowly administered via the applied vacuum.Intermittently during this process, the addition was slowed and/orhalted to allow reactor temperatures and vacuum to stabilize such thatconsistent distillation rates were maintained.

The cumulative recovery of distilled and condensed cyclics exceeded theknown siloxane content of the initial charge and the continual additionprocess was confirmed. Further, catalysis and distillation of thecontinuously added material resulted in the recovery of cyclics at arate consistent with that of the initial charge. After approximately 100g of siloxane material had been delivered from the storage vessel to thereactor, continuous addition was halted entirely. The reactor contentswere then distilled to dryness. Solids remaining at this point arecomprised of the filler component of the siloxane sealant and potassiumsilanolate catalyst. The remaining 1000 g of siloxane material was thenadministered to the reactor, via the applied vacuum, to evaluate thecatalytic activity remaining in the now dry reactor bed. Thedistillation and recovery of cyclics was re-initiated but at asubstantially diminished rate. This rate reduction was later determinedto be a result of decreased effective catalyst content. As the sealantentered to the reactor, pelletizing occurred and catalytic activity waslimited to the interface between the liquid pellet and its dry outercoating containing the actual catalyst.

Overall, this lab-scale operation confirms that the continual additionprocess, afforded by the unique reactor, decreases over-all catalystusage while maintaining efficient cyclics recovery even as total fillcontent within the reactor builds and viscosity increases.

Further, highly viscous materials, such as tubing or gum, and highlyfilled materials such as sealant and rubber have been successfullyrecycled in this reactor, in a single pass, taken to dryness, with noneed for subsequent processing of the remaining reactor contents forimproved yield. The ability to recycle highly filled materials alsoaffords the application of other inexpensive catalysts. Many siliconematerials are more efficiently catalyzed using p-toluene sulfonic acidor sulfuric acid. These catalysts are either expensive or have atendency to distill with the formed cyclic compounds. Pre-digestion orcatalysis of such materials using sulfuric acid can easily be performedfollowed by neutralization of the sulfuric acid to a sulfate salt. Thesalt simply adds to the total fill content of the material, now readyfor basic catalysis in the herein described process.

Example 2 Pilot Scale Trial Acid Pre-Digestion

The pilot trials in this example utilized a Model 1P1203JTB Porcupine®Processor originally developed by the Bethlehem Corporation andexclusively licensed by Advanced Thermal Solutions (ATS) of Emmaus, Pa.The primary reactor feature involves a heat-jacketed “U” trough designwith a hollow internal mixing shaft. This dramatically increases heattransfer surface area when the hollow shaft is filled with a heattransfer medium such as steam or hot oil. The specifications of thisreactor were as follows:

Diameter: 1 ft

Length: 3 ft

Volume: 2.1 ft³

Heat Transfer Area:

-   -   jacket: 9 ft²    -   mixing shaft: 15 ft²

Material of Construction: 316L Stainless Steel

Pressure rated to 50 psi and full vacuum at 550° F.

Maximum Hot Oil Temperature: 650° F.

Peripheral Equipment:

-   -   hot oil heater    -   heated vapor pipe    -   shell and tube vapor condenser    -   vacuum condensate reservoir    -   liquid ring vacuum pump system

During the course of the present invention it was discovered that forcertain types of silicone materials, only an acid catalyzed system ofdepolymerization is effective. In addition to the concerns of cost andthe potential for the acid to distill with the product, there was aconcern about the corrosive effects that these materials would have on astainless steel reactor. A corrosion study was performed prior toinitiating this example. The conclusions were that neither carbon steelnor stainless is suitable if one wished to extend the range ofperformance of the reactor. Laboratory results conducted during thecourse of the present invention suggested pre-digestion with acid priorto neutralization would render these materials susceptible to basecatalyzed depolymerization.

This acid pre-digestion procedure was implemented on silicone tubingwhich had been previously shredded down to a nominal size of ¼″. Thetubing contains nearly all cross-linked siloxanes with a smallpercentage of inert filler. A 35 lb sample of tubing was mixed with 35lb of siloxane fluid, for viscosity reduction, and 4.2 lb H₂SO₄. Thismixture was blended for five hours. Afterwards, 6.2 lb CaCO₃ was addedto neutralize the acid. Finally, a solution of 6.2 lb KOH dissolved in42 lb isopropyl alcohol was blended into the siloxane solution.

The Porcupine® Processor was loaded with the entire batch totaling 128.6lb. The isopropyl alcohol and oligomer were recovered over the course ofthe trial, and 27.2 lb of solids were removed at the end of the fivehour batch time (including reactor cool-down).

This trial yielded a 68.4% recovery. The poor mass-balance is attributedto the substantial loss of the distillates into the vacuum pump sealwater and the dispersed solids remaining on the 24 sq. ft of surfacearea within the reactor. Oligomer recovered from the seal water wascomprised primarily of hexamethylcyclotrisiloxane, or D₃s, due to theirlower boiling point than the D₄ and D₅ cyclic oligomers. This systemutilized city water to cool the condenser. A chiller would close themass-balance by preventing the loss of oligomer. Analysis of the solidsrecovered from the reactor revealed a siloxane content of 15%. Withinthe recovered solids, however, there were small pellets of undigestedtubing. It was determined that additional acid or an extended reactiontime during pre-digestion should be utilized.

Example 3 Pilot Scale Evaluation Highly-Filled Rubber

In this Example 35 lb of highly-filled silicone rubber was blended with35 lb of siloxane fluid using a high speed dispersion blade for 2.5hours. To this blend, was added a solution comprised of 5 lb of KOHdissolved into 28 lb of isopropyl alcohol. After blending for one hour,the contents were delivered to the Porcupine® Processor. The reactor wassealed, the hot oil setpoint was tuned to 200° F., and the vacuum in thereactor reached 27.5 in Hg. Following recovery of the bulk of theisopropyl alcohol, the hot oil set-point was increased to 410° F. Thetrial lasted five hours and was a success as the inert material went todryness.

The mass-balance of this conversion was 73.4%. Analysis of the solidsrevealed 6.4% siloxane content remaining. Improvements in materialmanagement will see this number reduced. Additionally, the limitedaccess to equipment, specific in design, for shearing many of thematerials, necessitated the addition of a diluent in the form ofsiloxane fluids. Laboratory results, and the fact that the blendedmaterials quickly build in viscosity during the course of thedistillation, demonstrates the feasibility of such conversions yieldingexcellent recoveries with little or no diluent necessary. This can berealized in a properly engineered, full-scale operation.

Although the present invention has been described with reference toparticular means, materials and embodiments, from the foregoingdescription, one skilled in the art can easily ascertain the essentialcharacteristics of the present invention and various changes andmodifications can be made to adapt the various uses and characteristicswithout departing from the spirit and scope of the present invention asdescribed above.

1: A method of processing polymer materials, highly filled or otherwisewhich comprises: providing a vessel having a heated side wall, anagitator, and at least one of: i) an additional heated structure, otherthan the heated side wall, within the vessel; and ii) means for forminga thin coat of material processed in the vessel on said heated sidewall; feeding a polymer material into the vessel; heating the polymermaterial in the vessel to a sufficient temperature to causedepolymerization of the polymer material into cyclic structures ormonomers; and collecting the monomers. 2: A method of processing polymermaterials, highly filled or otherwise according to claim 1, wherein thevessel comprises a thermal auger. 3: A method of processing polymermaterials, highly filled or otherwise according to claim 2, wherein theadditional heated structure comprises paddles of an agitator of thethermal auger. 4: A method of processing polymer materials, highlyfilled or otherwise according to claim 2, wherein the means for forminga thin coat of material processed in the vessel on said heated side wallcomprises paddles of an agitator or the thermal auger which areconfigured to have a clearance with respect to the heated side wall ofthe vessel which is sufficient to spread a thin coat of materialprocessed in the vessel on said heated side wall. 5: A method ofprocessing polymer materials, highly filled or otherwise according toclaim 3, wherein the polymer material comprises silicone material. 6: Amethod of processing polymer materials, highly filled or otherwiseaccording to claim 5, wherein the monomer is collected as a vapor andcondensed. 7: A method of processing polymer materials, highly filled orotherwise according to claim 1, wherein the vessel comprises a stirredtank reactor. 8: A method of processing polymer materials, highly filledor otherwise according to claim 6, wherein the additional heatedstructure comprises the agitator that extends into the stirred tankreactor. 9: A method of processing polymer materials, highly filled orotherwise according to claim 6, wherein the means for forming a thincoat of material processed in the vessel on said heated side wallcomprises the agitator which is configured to have a clearance withrespect to the heated side wall of the vessel which is sufficient tospread a thin coat of material processed in the vessel on said heatedside wall. 10: A method of processing polymer materials, highly filledor otherwise according to claim 7, wherein the polymer materialcomprises silicone materials. 11: A method of processing polymermaterials, highly filled or otherwise according to claim 10, wherein themonomer is collected as a vapor and condensed. 12: A method ofprocessing polymer materials, highly filled or otherwise according toclaim 1, further comprising providing a silanolate catalyst in thevessel with the polymer material. 13: A method of processing polymermaterials, highly filled or otherwise according to claim 12, wherein thesilnolate catalyst is formed by the addition of an alkali metal to bothends of a cyclic oligomer in the process of a ring-opening reaction. 14:A method of processing polymer materials, highly filled or otherwiseaccording to claim 1, wherein the polymer material comprises apre-digested silicone material. 15: A method of processing polymermaterials, highly filled or otherwise according to claim 14, wherein thepre-digested silicone material is pre-digested using an acid followed byneutralization to allow for efficient basic catalysis anddepolymerization. 16: A method of processing polymer materials, highlyfilled or otherwise according to claim 1, wherein vessel comprises athermal auger or thermal screw. 17: A method of processing polymermaterials, highly filled or otherwise according to claim 1, wherein themonomers are collected under vacuum. 18: A method of processing polymermaterials, highly filled or otherwise according to claim 1, wherein thepolymer is fed into the vessel without any solvent being present. 19: Amethod of processing polymer materials, highly filled or otherwiseaccording to claim 1, wherein the polymer is depolymerized without anysolvent being present. 20: A method of processing polymer materials,highly filled or otherwise according to claim 1, wherein the polymermaterials comprise at least one of a silicone fluid, a siliconeemulsion, a silicone sealant, a silicone rubber, a silicone gum, asilicon tubing, a silicone band and a silicone glove.